Exercise dumbbell



FIG. 1 is a front perspective view of an exercise dumbbell, showing my new design.

FIG. 2 is a left side view thereof.

FIG. 3 is a right side view thereof.

FIG. 4 is a front view thereof.

FIG. 5 is a rear view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines represent portions of the exercise dumbbell that are shown for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for an exercise dumbbell, as shown and described. 